My first set of advice would be to start seeing yourself as trim and healthy... whatever words excit you. If you keep calling yourself the fat guy you'll stay associated to the image that gives you.
A program that worked REALLY well for me was Tony Robbins Body You Deserve. It walks you through step by step dealing with alot of the mental stuff that happens when people 'diet'. Check it on on his site (there might even be links here to get to it).
My tips for success
2. Tell the world
3. Set rewards for yourself
4. Celebrate successes
It sounds like you're already well on your way for 1 and 2.
I look forward to sharing the journey with you!